THE grieving father of a 17-year-old boy who died after inhaling what he thought was laughing gas at a friend’s party in Radlett has warned teenagers against taking such substances.

A recent inquest at Herts Coroner’s Court was told that Joseph Benett believed he was taking nitrous oxide, or laughing gas, when offered a canister marked “Smelly Balloon”.

However tests later revealed that the canister contained a lethal cocktail of toxic gases including butane, which is used as a lighter fuel, and pentane, which is used to make polystyrene.

His friend Harry Ingram, 18, had brought the canister back from Israel, and the small print including the ingredients was written in Hebrew script.

The inquest heard that Harry had bought two of the canisters, which had each come with a pair of balloons, at a news agency in Tel Aviv, where he had been on holiday.

He said: “Out there, if you’re sitting at a bar on the beach, you will constantly hear the sound of these canisters being used. It’s very popular. People inhale it to have a laugh.

“It’s sold as laughing gas.”

Harry, who went to school with Joseph, invited five friends to his house in Radlett when he got home from Israel on August 31 last year.

The inquest heard that all the boys had tried inhaling nitrous oxide on previous occasions.

Harry and another friend tried inhaling the Smelly Balloon gas and felt light-headed. But when Joseph, who attended University College in Hampstead, had a go, his eyes rolled back and he stopped breathing.

An ambulance was called but by the time medics revived him 21 minutes later he had suffered massive irreversible brain damage.

Joseph remained in a coma for nearly a month before being transferred to a hospice where he died the following day, on September 27 – two months before his 18th birthday.

The inquest was also told that following Joseph’s death, Harry’s parents flew to Tel Aviv to confront the shopkeeper who sold their son the gas. She denied knowing it was dangerous but when they raised it with Israeli authorities, Smelly Balloon was withdrawn from sale in the country.

Coroner Edward Thomas recorded a verdict of accidental death, and said the boys had been playing “Russian roulette” by inhaling the gas – pointing out that even nitrous oxide could be lethal.

He added: “Inhaling this stuff is not always fatal, but it can be. And if you’re okay the first time, it doesn’t mean you’ll be okay the second time. It could kill you the first or the 10th time that you try it.”

In a statement after the inquest Joseph’s parents Rosann and David Benett, a photographer who works for the London Evening Standard, said: “His death is a tragedy beyond words and not a moment goes by without us thinking of our son.”

David was quoted in the Standard saying that Joseph’s death was a “warning to all those young guys who think they’re invincible. Don’t abuse anything if you don’t know what it is.”